Notes, abstracts, papers, exams and problems of Biology

ATP: What is ATP?Molecular Level: ATP is composed of 1 adenosine molecule (adenine + ribose) and 3 molecules of phosphate attached through high energy bonds.

• When energy is required, a phosphate group is cleaved off releasing free energy.

ATP  → ADP + P + ENERGY

• As a person goes about the daily schedules, the body is in constant high demand of ATP.

How does this body keep up with these demands?

• There are two methods the body uses to make new ATP, Anaerobic (without oxygen) and Aerobic (with oxygen).

• The system that is chosen for ATP production depends on the duration of the activity being performed.

Question 1:

Group the following as nitrogenous bases and nucleosides:

• Adenine, Cytidine, Thymine, Guanosine, Uracil and Cytosine.

Answer

Nitrogenous bases present in the list are adenine, thymine, uracil, and cytosine.

Nucleosides present in the list are cytidine and guanosine.

Question 2:

If a double stranded DNA has 20 per cent of cytosine, calculate the per cent of adenine in the DNA.

Answer

According to Chargaff’s rule, the DNA molecule should have an equal ratio of pyrimidine (cytosine and thymine) and purine (adenine and guanine). It means that the number of adenine molecules is equal to thymine molecules and the number of guanine molecules is equal to cytosine molecules.

% A = % T and % G = % C

If dsDNA has 20% of cytosine, then according to... Continue reading "Understanding DNA: Bases, Replication, and Functions" »

• The outer ear: it is formed by the pinna and the auditory canal.
• The middle ear: a cavity in the eardrum that reaches the oval window and the round window.
• The inner ear: formed by the membranous labyrinth.
• Sweat gland: this secretes sweat, cooling the body surface when it is necessary and removing certain waste substances.
• Sebaceous gland: these secretes substances that lubricate the skin and hair.
• Taste buds: are located inside the mouth especially on the tongue.
• Long bones: these are long and contain spongy bone tissue at either end, as well as compact bone.
• Short bones: these are rounded and mostly made up of spongy bone tissue.
• Flat bones: these are plate-shaped. Formed by an inner layer of bone tissue surrounded by two layers of compact bone

Environmental Factors

Characteristics of the environment that affect living things are called environmental factors. They can be abiotic (related to non-living things) or biotic (related to living things).

Biotic and abiotic factors

⦁ Abiotic factors: Physical and chemical conditions that affect living things.

The main abiotic factors are water, light, temperature, soil, pH, humidity, and nutrients found in water and soil. Some abiotic factors are more important than others depending on the location they are in.

• Sunlight is essential for life on Earth to exist.
• The concentration of oxygen in the atmosphere decreases as altitude increases.
• Temperature is a decisive factor in the physiological activity of living things.
• Water is an essential substance

The Internal Environment

• Refers to the fluids that surround the cells.
• Temperature and composition must be stable for the correct working of cells.
• This internal environment is maintained by the organ systems of the body.
• Interstitial fluid (plasma): Surrounds and bathes the cells.
• Blood and lymph: Collect and distribute substances for the cells (O2, nutrients) and remove waste.

The Circulatory System

• Carries nutrients and oxygen throughout the body and collects waste (blood): Blood Circulatory System.
• Returns excess interstitial fluid to the blood.
• Transports fat to the blood.
• Defends the immune system (lymph): Lymphatic System.

The Lymphatic System

• Lymph capillaries:
  • Thin vessels closed at one end.
  • Collect excess interstitial fluid.
• Lymphatic vessels:

Human Body Systems

1. Respiratory System: The purpose of this system is to take in air, filter it, and take it to the tissues responsible for gas exchange. Oxygen is then transported by blood to all the tissues in the body. Carbon dioxide, a waste product, is reabsorbed and excreted from the body.
2. Skeletal System: This system forms the basic framework of the body. It supports and protects all internal organs. Bones serve as levers (with the attached muscles) for movement, produce blood cells, and store calcium salts, which can be absorbed into the blood when there is not enough calcium in the diet.
3. Endocrine System: The secretion of hormones, which regulate the body's functions chemically, is the function of this system.
4. Urinary System: This system

Keystone Species

Predators that maintain the balance of other species within the ecosystem.

Trophic Cascade

Ecological phenomenon triggered by the removal or addition of top predators, causing changes in the ecosystem through the food chain.

Green World Hypothesis

Hypothesis stating that predators control the number of herbivores.

Food Chains

Illustrate a single pathway of feeding relationships.

Food Web

Represents the complex relationships between multiple species and their various feeding interactions.

10% Law

As energy transfers through trophic levels, 90% is lost, with only 10% retained. This loss occurs due to metabolic reactions, growth and repair, movement, and heat.

Energy Flow

The movement of energy through the food chain.

Energy Pyramid

Measured

The Cori Cycle: Recycling Lactic Acid

After lactate (often referred to as lactic acid) is produced, it is transported by the blood to the liver. In the liver, most of the lactate is converted back to glucose. During periods of rest, this newly formed glucose is efficiently stored as glycogen through a process known as glycogenesis. Approximately one-sixth of the lactate is oxidized to carbon dioxide.

Essentially, during the Cori Cycle, lactic acid is recycled. It is converted to pyruvate, which can then be used for the future conversion to glucose and subsequently stored as glycogen.

Energy Sources Beyond Carbohydrates

While the primary source of energy during physical activity typically comes from carbohydrates and other glucose sources (like... Continue reading "Cori Cycle, Lactate Metabolism, and Fat Energy Pathways" »

Healthy Habits for Sense Organs

Provide multidirectional protection. Eat a healthy diet, avoid harmful substances, have routine examinations, maintain good hygiene, and avoid injuries.

Specific Preventive Measures

Eyes

• Use sunglasses to prevent overexposure to intense light.
• Read or do precision work in bright light.
• Do not rub your eyes when they itch.
• Rest your eyes periodically; look into the distance regularly when working at the computer.

Ears

• Remove excessive earwax by washing the outer ear; do not insert anything into the auditory canal.
• Avoid loud noise; use headphones at a moderate volume to prevent hearing loss.

Skin

• Shower or wash daily.
• Avoid UV radiation, which causes severe sunburn and skin cancer.
• Cover your body or use sunscreen during the